Wear lining



. ssoN Ei-AL WEAR LQINING FIGS 2 Sheets-Sheet 2 United States Patent M 3,107,867 WEAR LINHNG Assar Natanael Svensson, Ersmarlr, and Bertil Brandt,

Grangesberg, Sweden, assignors to Skelleftea Gunsmifabriks A.-B., Ersmark, Sweden, a joint-stock company of Sweden Filed Feb. 23, 1962, er. No. 175,2-t2 Claims priority, application Sweden Feb. 25, 1961 11 Claims. (Cl. 2411l2.)

This invention relates to a lining of rubber adapted to protect rotary drums such as ball mills or tube mills or the like comprising a plurality of adjacent sections constituting partly separate lifting means (so-cflled lifters) and partly separate lining plates disposed between the said lifting means.

A wear lining of rubber is described previously in Swedish patent specification 159,488. According to this proposal, the rubber lining plates as well as the lifting means (so-called lifters) are made in one piece. In view of the fact, however, that there arose difficulties in producing rubber of sufiicient thickness, the said proposal was never realized. If these ditficulties were overcome, there would arise new difiiculties with respect to the mounting of the lining in the drum and its replacement in the event of faults or due to wear.

A wear lining of steel comprising a plurality of adjacent sections consisting partly of separate lifting means (so-called lifters) and partly of separate lining plat-es disposed between the said lifters are previously described in Swiss patent specification 272,033. This lining type has been in use for many years, but it shows several serious drawbacks. It is, for example, very heavy, wears rela tively quickly and includes serious risk when being mounted.

It is :the object of this invention to produce an improved wear lining which eliminates the aforesaid difficulties and drawbacks entirely or partially, in addition to that it renders possible other advantages which appear from the description as follows.

The invention is characterized in that the lifting means are provided with an internal longitudinal slot with means, for example bars with threaded pins welded thereon, inserted or vulcanized therein for holding the lifting means. The sections are preferably arranged along the generatrices in the drums, and the rubber lining plates along their longitudinal edges provided with recesses, the lifting means preferably being provided with corresponding profile. The said lifting means are anchored in the wall of the drum. The holding or anchoring occurs in such a manner that there is produced a pressure against the recesses of the rubber lining plates, with the result, that the lifting means act as locking means for the plates. There is no objection to anchor even the plates in the wall of the drum, but this is unnecessary if there is normal distance between the lifting means.

The means for holding the lifting means comprise preferably bars with threaded pins welded thereon. As other examples of holding means may be mentioned bars with threaded holes or sleeves adapted to screw bolts therein from the outsideof the Whilst the lining is being mounted. The bars may have the same length as the lifting means or be divided in several sections.

3,107,357 Patented Oct. 22, 1963 The lifters, in order to have the desired effect for grinding in the mill, must be given a certain height above the rubber lining plates, which plates, in their turn, must have a certain, rather considerable thickness. Preferable thicknesses are 40-80 The relation between the thickness of the rubber lining plates and the distance between the highest point of the lifting means and the inside of the sheet casing should be between 0.25 and 0.95, preferably between 0.50 and 0.70. The said values cannot be considered to be critical but should be regarded primarily as suitable. The height above the plates which the lifters should have from the beginning depends on several factors, for example on the distance between the lifters, the grinding volume etc. When the lifters are Worn to about half the lifting height, it is economically advantageous to mount new lifters or to replace the Worn rubber and vulcanize new rubber thereon. With continuing wear the wear of the rubber lining plates increases considerably. As long as the lifters have suitable height above the plates, the plates are not subjected to wear, or only to a very small eXent.

The sections of Wear-resistant material are preferably made of unreinforced natural rubber with a hardness of 40-80 Shore and with high rubberycontent. The manufacture of the lifters is preferably carried out by extrusion or compression moulding.

The lifters need not necessarily be made in one piece but may be jointed while being mounted. In this case it is preferable to insert sealing means, preferably of unreinforced soft rubber hose. The joints of two adjacent parallel lifters should be staggered in relation to one another. Sealing elements may possibly be inserted between the rubber lining plates.

According to a modification of the present invention, the rubber lining plates may be made of more or less entirely covering material. The lifting means may in such a case be arranged above the material or in recesses cut into the upper surface of the material. Such a lining renders greater difiiculties in mounting due to the larger rubber fabric, but it may include advantage-s due to a simpler replacement of the lifting means.

The invention will be described in greater detail in the following, reference being made to the accompanying drawings, whereon FIG. 1 shows in a schematic manner the cross-section of a mill, FIG. 2 is an elevation partly in section on line II of FIG. 1; FIG. 3 is an enlarged cross section of a detail of a lifting means; FIG. 4 is an enlarged cross sectional view of a detail of another embodiment of the lining according to the invention, and FIG. 5 is an enlarged cross sectional view of a sealing element between two end surfaces of a lifting means in several parts.

FIG. 1 shows in a schematica-l manner how the mill drum 1 is lined with lining plates of rubber 2, and lifting means 3.

FIG. 2 is a side view partially in section along the line II-II in FIG. 1 andshows how the lining is divided in sections disposed along generatrices in the circular drum.

FIG. 3 shows an example of how the rubber lining plates 2 are provided with recesses along their longitudinal edges. The lifters 3 are provided with corresponding profiles in such a manner, that the lifters act as locking means for the plates 2. The lifters 3 are provided with grooves or 5 7 wedded thereon which protrude through openings in drum 1 and are engaged by nuts 7a.

FIG. 4 shows another embodiment with entirel covering rubber lining plate 8 including grooves 9 wherein the lifters 10 ane arranged. In this embodiment the bars 11 attached to lifters 10 by vulcanizing are utilized with internally threaded sleeves 1'2 welded thereon.

FIG. shows in a schematic manner how sealing elements 12 are used in the joints between two end surfaces of a lifter divided in two par-ts 13a and 1312.

When testing by comparison t-Wo mills, one of them being provided with a wear lining according to this invention and the other one provided with a Wear :lining of steel of highest quality according to Swiss patent specification No. 272,033, the following result is obtained:

With respect to the wear lining according to the present invention, the calculated minimum time of 18,000 hours is based on the replacement of the lifters when they are worn to half their height. Thereby, only the lifters have to be replaced. As regards the wear lining according to Swiss patent specification 272,033, it was, however, necessary to exchange both the lifters and the lining plates already after 7,000 hours. The mounting of the wear lining according to the present invention was simple and substantially without risk, while the mounting of new wear lining in the other mill was time wasting and particularly full of for the Workers.

What we claim is:

1. Wear lining of rubber for rotary drums, comprising a plurality of adjacent sections of separate rubber lifting means and separate rubber lining plates disposed between the said lifting means, the said lifting means being provided with an internal slot having bars inserted therein, said bars having threaded pins Welded thereon for holding the lifting means.

2. Wear lining of rubber for rotary drums, comprising a plurality of adjacent sections of separate rubber lifting means and separate rubber lining plates disposed between the said lifting means, the said lifting means being provided with an internal slot wherein bars having threaded holes are inserted for holding the lifting means.

3. Wear lining of rubber for rotary drums, comprising a plurality of adjacent sections of separate rubber lifting means and separate rubber lining plates disposed between the said lifting means, the said lifting means each being provided with an internal slot wherein bars having threaded sleeves welded thereon are inserted for holding the lifting means.

4. A modification of the wear lining according to claim 1, and in which the rubber lining plates are made at least partially of covering material and that the lifting'means are arranged in recesses cut into the upper surface of the material.

5. Wear lining according to claim 1, characterized in that the sections are arranged along the generatr-ices in the drums.

6. Wear lining according to claim 5, and in which the rubber lining plates are along their longitudinal edges provided with recesses, and that the lifting means are provided with corresponding profiles.

7. Wear lining according to claim 6 and in which the lifting means are anchored in the wall of the drum.

8. Wear lining according to claim 7, and in which the rubber lining plates are held to the Wall of the dmm by a pressure exerted by the lifting means on the bottom walls of the recesses in the longitudinal edges of the rubber lining plates.

9. Wear lining according to claim 1 and in which the ratio between the thickness of the rubber lining plates and the distance between the highest point of the lifting means and the wall of the drum is between 0.25 and 0.95, preferably between 0.50 and 0.70.

10. Wear lining according to claim 1, and in which the sections are made of lumeinforced natural rubber with a hardness of 40-80 Shore and with high rubber content.

ll. Antodifieation of the wear lining according to claim 1, and in which the rubber lining plates are made at least partially of covering material and that the lifting means are arranged above the covering material.

References Cited in the file of this patent UNITED STATES PATENTS =1,'92l,672 Haushalter Aug. 8, 1933 2,058,257 Porteous Oct. 20, 1936 2,611,546 Posselt Sept. 23, 1952 2,867,387 Dodd-s et al. Ian. 6, 1959 FOREIGN PATENTS 178,729 Germany Nov. 17, 1906 

1. WEAR LINING OF RUBBER FOR ROTARY DRUMS, COMPRISING A PLURALITY OF ADJACENT SECTIONS OF SEPARATE RUBBER LIFTING MEANS AND SEPARATE RUBBER LINING PLATES DISPOSED BETWEEN THE SAID LIFTING MEANS, THE SAID LIFTING MEANS BEING PROVIDED WITH AN INTERNAL SLOT HAVING BARS INSERTED THEREIN, SAID BARS HAVING THREADED PINS WELDED THEREON FOR HOLDING THE LIFTING MEANS. 